摘要:

AbstractYoung dystrophic (dy) murine muscle is capable of ( spontaneous) regeneration (i.e., regeneration in the absence of external trauma); however, by the time the mice are 8 weeks old, this regeneration ceases. It has been suggested that the cessation of regeneration in dystrophic muscle may be due to exhaustion of the mitotic capability of myosatellite cells during the early stages of the disease. To test this hyptothesis, orthotopic transplantation of bupivacaine treated, whole extensor digitorum longus muscles has been performed on 14 to 16‐week‐old 129 ReJ/++ and 129 ReJ/dydy mice. The grafted dystrophic muscle is able to produce and maintain for 100 days post‐transplantation 356 ± 22 myofibers, a number similar to that found in age‐matched dystrophic muscle. The ability of old dystrophic muscle to regenerate subsequent to extreme trauma indicates that the cessation of ( spontaneous) regeneration is due to factor(s) other than the exhaustion of mitotic capability of myosatellite cells. Moreover, there is no significant difference in myosatellite cell frequencies between grafted normal and dystrophic muscles (100 days post‐transplantation). Myosatellite cell frequencies in grafted muscles are similar to those in age‐matched, untraumatized muscles. While grafting of young dystrophic muscle modifies the phenotypic expression of histopathological changes usually associated with murine dystrophy, grafts of older dystrophic muscle show extensive connective‐tissue infiltration and significantly fewer myofibers than do grafts of age‐matched normal muscle. As early as 14 days post‐transplantation, it is possible to distinguish between grafts of old, normal and dystrophic muscles. It is suggested that the connective tissue stroma, present in the dystrophic muscle at the time of transplantation, may survive the

ISSN:0002-9106    

DOI:10.1002/aja.1001810102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractComponents of the testis and cytoplasmic organelles in Leydig cells were quantified with morphometric techniques in hamster, rat, and guinea pig. Testosterone secretory capacity per gram of testis and per Leydig cell in response to luteinizing hormone (LH) (100 ng/ml) stimulation was determined in these three species from testes perfused in vitro. Numerous correlations were measured among structures, and between structures and testosterone secretion, to provide structural evidence of intratesticular control of Leydig cell function.Testosterone secretion per gm testis and per Leydig cell was significantly different in the three species: highest in the guinea pig, intermediate in the rat, and lowest in the hamster. The volume of seminiferous tubules per gm testis was negatively correlated, and the volumes of interstitium. Leydig cell, and lymphatic space per gm testis were positively correlated with testosterone secretion. No correlations were observed between volumes of blood vessels, elongated spindle‐shaped cells, or macrophages per gm testes and testosterone secretion.The average volume of a Leydig cell and the volume and surface area of smooth endoplasmic reticulum (SER) and peroxisomes per Leydig cell were positively correlated, and the volume of lysosomes and surface area of inner mitochondrial membrane per Leydig cell were negatively correlated with testosterone secretion. No correlations were observed between volume and surface area of rough endoplasmic reticulum (RER), Golgi apparatus, and lipid, and volume of ribosomes, cytoplasmic matrix, and the nucleus with testosterone secretion per Leydig cell.These results suggest that Leydig cell size is more important than number of Leydig cells in explaining the difference in testosterone‐secreting capacity among the three species, and that this increase in average volume of Leydig cell is associated specifically with increased volume and surface are of SER and peroxisomes. An important unresolved question is what is the role of peroxisomes in Leydig cell steroidogene

ISSN:0002-9106    

DOI:10.1002/aja.1001810103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe present study reports on the fine structure of human costal cartilage at different ages in order to obtain information on the morphogenesis of amianthoid fibers. Our results reveal an overall increase of collagen fibril diameter with increasing age, even in areas with no signs of amianthoid transformation. Ultrastmctural evidence is presented that this increase in diameter is due to a gathering of the preexisting collagen fibrils. The age‐related change in collagen fibril diameter is paralleled by changes in the composition and ultrastructural appearance of cartilage proteoglycans (as revealed by acridine orange staining). Acridine‐orange‐positive filaments indicative for proteoglycans are markedly reduced in size with advancing age in centrally located regions of costal cartilage. Treatment with testicular hyaluronidase previous to acridine‐orange staining leaves these small proteoglycan filaments unaffected. By contrast, the filaments visible after acridine‐orange staining in the extracellular matrix near to the perichondrium are susceptible to hyaluronidase treatment. Infrequently, a sharp increase in collagen fibril diameter can be observed in territorial matrix areas of degenerating chondrocytes. This observation is conspicuous at ages of 10 and 20 years. Amianthoid transformation is characterized by the appearance of collagen fibrils strictly arranged in parallel. These amianthoid fibers are embedded in a matrix rich in small acridine‐orange‐positive filaments similar to the proteoglycan filaments observed in centrally located matrix regions. It can be concluded that extensive remodelling not only of the collagen fibrils but also of the cartilage proteoglycans is involved in the development of amianthoid t

ISSN:0002-9106    

DOI:10.1002/aja.1001810104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe presence and distribution of mesenchymal components in the extracellular matrix during lung development in the chick embryo (from 5½/6 to 18 incubation days) has been examined histochemically. Attention is focused mainly on glycosaminoglycans (GAG). Morphological reconstructions show three main stages: first (5½/6–8 days), formation of 2nd‐order branching; second (9–12 days), proliferation of para‐bronchi and third (from 13th day on), formation of air capillaries. In the first phase, hyaluronic acid (HA) prevails around the mesobronchus, but chondroitin sulfate (CS) dominates the 2nd‐order branches. Basement membranes of 2nd‐order branches are strongly positive for sulphated GAG. In the second phase, CSA increases in the ground substance of mesenchyme. This increase is irregular, being smaller in older areas (mesobronchus, branches of 2nd order) and larger in the more recent parabronchi, which extend into the lateral and dorsal areas of the rudiment. An increase in both sulfated GAG and glycoprotein (GP) occurs in basement membranes. In the third phase, GAGs are uniformly distributed in the mesenchymal septa and around the interlobular vascular network. This concentration decreases while the GP concentration increases. Basement membranes around every branch of the 1st, 2nd, and 3rd orders possess large quantities of GP. Mesenchymal GAG occurs in every stage of lung development, temporally correlating with the morphogenesis and differentiation of epithelium. Our results provide necessary information, which has not been available so far. Experimental studies specifically designed to clarify the developmental significance of such a heterogeneous distribution may be interpreted in the light of thi

ISSN:0002-9106    

DOI:10.1002/aja.1001810105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe localization of GABA‐like immunoreactivity in the locus ceruleus of rats was studied by the peroxidase‐antiperoxidase (PAP) method using a purified antibody raised against GABA applied to paraffin sections, with counterstaining by cresylecht violet, and to floating sections for preembedding immunoelectron microscopy. A few medium‐sized and some small neurons showed GABA‐like immunoreactivity in both nuclei and perikarya. The preferential localization of these immunopositive neurons in the marginal parts of the locus ceruleus suggests that they are inhibitory local circuit neurons located between this center and the afferent fiber systems. Some of the immunoreactive neurons displayed homogeneous and heterogeneous ( paired cells) patterns. Occurrence of the GABA‐GABA interaction is indicated. Immunopositive bouton forms are located close to every positive and negative neuron. Electron microscopy confirms GABA‐like immunoreactivity in both medium‐sized and small neurons of the locus ceruleus and demonstrates that immunoreactive boutons are axosomatic and axosoma spine symmetric synapses on immunopositive and immunonegative cell bodies. These immunocytochemical results support the existence of inhibitory interneurons in the l

ISSN:0002-9106    

DOI:10.1002/aja.1001810106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe developing anlage of the choroid plexus and supraependymal structures in the fourth ventricular roof plates of nine normal human embryos ranging from Carnegie stages 14 to 19 were investigated with scanning electron microscopy. In the human embryos at stage 18, the first semimacroscopic choroidal anlage developed in the form of bilateral evaginations that ran dorsomedially and caudally from the bilateral corners of the rhombencephalon. The anlage became evident with even smaller and parallel ridges in the embryo at stage 19. Embryos at earlier stages exhibited surface membrane modifications such as convexity, microvilli, cilia, and spherical protrusions at the middle one‐third of the rhombencephalon, which corresponded to the future choroidal anlage region.Two morphologically different groups of supraependymal cells (SE cells) were elucidated throughout the stages examined. Type 1 SE cells has spindle or teardrop‐like bodies, frequently with one or more long cy‐toplasmic processes. Type 2 SE cells were globular, with numerous fine pseudopodial processes. Type 1 SE cells were distributed mainly at the future choroidal anlage regions or on the anlage itself and were less frequently located at the rostral end of the roof. We found no general pattern in the distribution of type 2 SE cells. Supraependymal fibers (SE fibers) wete seen as fine processes that were distributed similarly to type 1 SE cells and extended transversely for a long dis

ISSN:0002-9106    

DOI:10.1002/aja.1001810107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractWe report here recent findings on the sperm maturation antigen SMA4, which is secreted by holocrine cells of the distal caput epididymis and binds to the flagellar surface of mouse sperm during epididymal transit.Washed sperm from the caput and corpus epididymides of mice were examined by immunofluorescence and SDS‐PAGE using wheat germ agglutinin, which binds specifically to SMA4 as a primary probe. Results indicate that sperm first exhibit WGA reactivity on their flagellae in the region of the distal caput, and that the appearance of WGA receptors is due to the binding of a 54‐Kd glycoprotein (SMA4) to the cell surface. Extracts of epididymis containing SMA4 were tested for their ability to bind to the surfaces of caput and corpus sperm. Caput sperm surfaces bound SMA4 in&temperature‐independent manner, and binding occurred in the presence of enzyme inhibitors., suggesting a nonenzymatic process. Biochemical studies revealed that SMA4 contains disulfide bonds which stabilize it on the sperm surface and restrict its mobility. Terminal carbohydrate residues of the molecule are sialic acids. The addition of SMA4 to caput sperm flagellae prevented tail‐to‐tail agglutination, normally seen when caput sperm are diluted into saline; and SMA4 was able to disperse clumps of agglutinated caput sperm. The data suggest that a primary function of SMA4 is to prevent tail‐to‐tail agglutination of sperm during storage in t

ISSN:0002-9106    

DOI:10.1002/aja.1001810108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe dynamic spatial reconstructor–a unique, high speed, volume‐scanning, X‐ray computed tomographic imaging system–was utilized to examine canine renovascular anatomy and renal circulation in situ. In each of the four kidneys examined in this study initial scans were done during bolus injections of angiographic contrast material into the renal artery. A subsequent scan was then performed following an injection of methyl‐methacrylate‐based casting compound that had been contrast enhanced with ethiodol. After the scans, each kidney was removed, and its parenchyma was digested in potassium hydroxide to expose the vascular cast. Comparison of casts with their reconstructed images and with images obtained during injection of contrast material showed that interlobar arteries and occasionally arcuate arteries could be clearly detected. Although discrete vessels less than 1 mm in diameter could not be resolved, dynamic changes in parenchymal distribution of density during passage of contrast material allowed interpretation of flow through the multiple capillary beds of the kidney. Such analysis indicated that maximal density was in the outer‐middle zone of the cortex throughout the duration of the scan. Analysis of artery‐to‐vein transit time showed arrival of contrast material in the renal vein as soon as 3 sec, and continuation for longer than 8 sec, after the renal artery bolus. In conclusion, renal circulation in the dog can be discretely visualized with the dynamic spatial reconstructor up to the level of the arcuate arteries; however, capillary flow as a whole can be followed through the cortex, and the results suggest the presence of both rapid and slow components of peritu

ISSN:0002-9106    

DOI:10.1002/aja.1001810109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe morphogenesis of the sexually indifferent gonad of the primateGalago crassicaudatus crassicaudatuswas studied by high‐resolution light microscopy and electron microscopy in 15 embryos aged 26 to 33 days. Onset of gonadal development follows the morphogenesis of the mesonephros by a conspicuous interval and is identified as the time when the first primordial germinal cells arrive in the region ventral to the central third of the mesonephros; this is followed by intense proliferation of the coelomic mesothelial cells lining the area. They become organized into short piles that deepen in the underlying mesenchyme, enclosing the germinal cells in the process. Rapidly, the piles become confluent forming a compact mass, the gonadal blastema, which is soon cleaved into gonadal cords by stroma and vascular lacunae. The mesonephros becomes involved in the morphogenesis of the gonad only in late stages of development when anatomic continuities become established between the capsules of its regressing glomeruli and the elongating gonadal rete cords. These observations show that in the Galago the somatic cells of the gonadal blastema, i.e., the precursors of the definitive testicular and ovarian sustentacular cells, derive from the coelomic mesothelium in contrast to other mammals, e.g., ruminants and rodents, where they are of mesonephric derivation. This important point is discussed in light of the differences that exist among species with regard to the structural complexity, functionality, and stages of differentiation/ involution of their mesonephroi on the one hand, and the time of gonadal development on the othe

ISSN:0002-9106    

DOI:10.1002/aja.1001810110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001810101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY